International patent application Nos. PCT/US95/02691, PCT/US95/06758, and PCT/US96/09653, are incorporated in their entirety herein by reference, and disclose fuel compositions and combustion techniques for achieving vapor phase combustion based on an enhanced combustion structure (“ECS”). This enhanced combustion structure includes a combustible metallic and free radical generating oxygenated compound. It has been found that such free radical generating oxygenates include C2-C12 aldehydes, aldehydic acids, C2-C12 ethers, C1-C15 alcohols, C2-C12 oxides, C3-C15 ketones, ketonic acids, C3-C15 esters, othroesters, C3-C12 diesters, C5-C12 phenols, C5-C20 glycol ethers, C2-C12 glycols, C3-C20 alkyl carbonates, C3-C20 dialkyl carbonates, C3-C20 di-carbonates, C1 to C20 organic and inorganic peroxides, hydroperoxides, carboxylic acids, amines, nitrates, di-nitrates, oxalates, phenols, acetic acids, boric acids, orthoborates, hydroxyacids, orthoacids, anhydrides, acetates, acetyls, formic acids, nitrates, di-nitrates, nitro-ethers, which can meet minimum burning velocity (BV) and latent heats of vaporization (LHV) requirements of aforementioned PCT Applications. Specific compounds can be found in detail in Organic Chemistry 6 th Ed, T. W. G. Solomons, John Wiley & Sons, N.Y., (1995), Physical Chemistry, 5 th Ed, P. W. Atkins, Oxford University Press, U.K. (1994), Physical Organic Chemistry, 2 Ed, N. S. Issacs, John Wiley & Sons, N.Y. (1995) and Lange's Handbook of Chemistry, 14 th Ed, J. A. Dean, McGraw-Hill, N.Y. (1992), and their minimum BV/LHV requirements in aforementioned PCT Applications, which are herein by incorporated by reference.
Said enhanced combustion structure oxygenates, when in combination with a combustible non-lead metal or non-metal (as set forth below), exhibit high heats of enthalpy capable, improved combustion, thermal efficiency, fuel economy, and power. Of particularly interest to this invention are the enhanced combustion struture oxygenates of symmetrical dialkyl carbonates, especially dimethyl and diethyl carbonates.
However, it has been reported symrrietrical dialkyl carbonates, such as dimethyl carbonate can be problematical fuel additives due to their potential instability in fuel compositions, which can result in undesired hydrolysis in acidic and aqueous environments. See EPO Application #91306278.2 Karas. Thus, it would be reasonable to expect fuels containing lower dialkyl carbonates to store and perform optimally only when in moderately strong or strongly alkaline environments, i.e., pH's exceeding 11 or more. Fuels-having pH's lower than 11, e.g. moderately alkaline, nuetral and acidic would be expected to be problematic.
In addition, conventional thinking and regulatory standards encourage the utilization of more refined less viscous base fuel hydrocarbons. The longer chain or more complex hydrocarbons, e.g., heavy oils, heavy fuel oils, diesels, etc., are typically not preferred as fuels due to handling, emission and combustion concerns.